package bigdata.mapreduce;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;

public class Reduplication {
	public Reduplication() {}
	
	public static class Map extends Mapper<Object,Text,Text,NullWritable>{
		private static Text text=new Text();
		
		@Override
		public void map(Object key,Text value,Context context)
				throws IOException, InterruptedException{
			text=value;
			context.write(text, NullWritable.get());
		}
	}
	
	public static class Reduce extends Reducer<Text,NullWritable,Text,NullWritable>{
		@Override
		public void reduce(Text key,Iterable<NullWritable> values,Context context) 
				throws IOException, InterruptedException {
			context.write(key, NullWritable.get());
		}
	}	

	public static void main(String[] args) throws IOException, ClassNotFoundException, InterruptedException {
		// TODO Auto-generated method stub
		Configuration conf=new Configuration();
		conf.set("fs.defaultFS", "hdfs://localhost:9000");
		String[] otherArgs=(new GenericOptionsParser(conf,args)).getRemainingArgs();
		if(otherArgs.length<2) {
			System.err.println("Usage:Reduplication<in>[<in>...] <out>");
			System.exit(2);
		}
//		else {
//			for(int i=0;i<otherArgs.length;i++) {
//				System.out.println(otherArgs[i].toString());			
//			}
//			System.out.println(WordCount.class.toString());
//			System.exit(0);
//		}	
		
		Job job=Job.getInstance(conf,"Reduplication");
		job.setJarByClass(WordCount.class);
		
		job.setMapperClass(Reduplication.Map.class);
		job.setReducerClass(Reduplication.Reduce.class);
		
		job.setMapOutputKeyClass(Text.class);
		job.setMapOutputValueClass(NullWritable.class);
		
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(NullWritable.class);
		
		for(int i=0;i<otherArgs.length-1;i++) {
			FileInputFormat.addInputPath(job, new Path(otherArgs[i]));			
		}
		
		FileOutputFormat.setOutputPath(job, new Path(otherArgs[otherArgs.length-1]));
		
		System.exit(job.waitForCompletion(true)?0:1);		
	}
	

}
